1. Field of the Invention
The present invention relates to an optical switching device and an optical switching method therefor, and in particular, to a single-stage optical switching device having a recirculating structure and an optical switching method therefor.
2. Description of the Related Art
In general, many kinds of multiple interconnection networks (MINs) have been used in telephone switching systems for the past forty years, including Clos, Benes, Omega, Baynan, Baseline, Flip, and etc.. Research has been conducted on other kinds of networks for use in broadband switching systems or parallel computing systems.
The Omega network, obtained by cascading shuffle/exchange networks in log.sub.2 N (N is both the number of input ports and the number of output ports) stages, is very important since it facilitates integration due to its symmetrical structure and thus can be used as a switching device in a broadband switching system or a parallel computing system requiring large switching capability. Therefore, the Omega network is suitable for modern technologies, especially, OEICs (i.e., optoelectrical integrated circuits) and PICs (i.e., photonic integrated circuits).
The non-blocking Omega network can increase its switching capability by increasing the number N of switch stages, and additionally have a batcher sorting network, a comparison/blocking circuit network, and a concentration circuit, for sorting and self-routing. However, such a conventional optical switching network shows limitations in realizing a large switching network system since it increases its switching capability by increasing the number of switch stages, resulting in a too bulky switch.
The following patents each disclose features in common with the present invention but do not teach or suggest an optical switching device having a recirculating structure and optical switching method therefor in accordance with the present invention: U.S. Pat. No. 5,526,352 to Min et al., entitled Integrated Low Complexity Broadband Multi-Channel Switch, U.S. Pat. No. 5,287,346 to Bianchini Jr. et al., entitled Packet Switch, U.S. Pat. No. 5,440,549 to Min et al., entitled Broadband Multi-Channel Switch With Multicasting Capability, U.S. Pat. No. 4,893,304 to Giacopelli et al., entitled Broadband Packet Switch With Combined Queuing, U.S. Pat. No. 5,546,484 to Fling et al., entitled Fiber Optic Switch Using Polished-Type Directional Coupler, U.S. Pat. No. 5,604,617 to Burton, entitled Telecommunications Switching Element, U.S. Pat. No. 5,402,256 to Spanke, entitled Optical Time Slot Interchanger Apparatus And Method Of Operation, U.S. Pat. No. 5,416,769 to Karol, entitled Controlled-Feedback Packet Switching System, U.S. Pat. No. 4,856,862 to Passmore et al., entitled Optical Storage Method And Apparatus, U.S. Pat. No. 5,258,978 to Cloonan et al., entitled Space-Division Switching Network Having Reduced Functionality Nodes, U.S. Pat. No. 5,122,892 to Cloonan et al. entitled Space-Division Switching Network Having Reduced Functionality Nodes, U.S. Pat. No. 5,077,483 to Cloonan et al., entitled Network Topology For Reduced Blocking And Photonic System Implementation Thereof U.S. Pat. No. 5,023,864 to Cloonan et al., entitled Crossover Network Utilizing Two-Dimensional Arrays Of Nodes, U.S. Pat. No. 5,546,393 to Minc, entitled Asynchronous Transfer Mode Data Cell Routing Device For A Reverse Omega Network, U.S. Pat. No. 5,319,788 to Canfield et al., entitled Modified Batcher Network For Sorting N Unsorted Input Signals In Log.sub.2 N Sequential Passes, and U.S. Pat. No. 5,469,284 to Haas, entitled Optical Packet Switch.